docs: add example of src overwriting for US umami.is tracking

data/siteMetadata.js

@@ -27,6 +27,9 @@ const siteMetadata = {
     umamiAnalytics: {
       // We use an env variable for this site to avoid other users cloning our analytics ID
       umamiWebsiteId: process.env.NEXT_UMAMI_ID, // e.g. 123e4567-e89b-12d3-a456-426614174000
+      // You may also need to overwrite the script if you're storing data in the US - ex:
+      // src: 'https://us.umami.is/script.js'
+      // Remember to add 'us.umami.is' in `next.config.js` as a permitted domain for the CSP
     },
     // plausibleAnalytics: {
     //   plausibleDataDomain: '', // e.g. tailwind-nextjs-starter-blog.vercel.app